1. Field of the Invention
The present invention relates to a protective clip that may be affixed to a motor vehicle steering linkage ball joint, and in particular to a clip that presents a heat shield between a rubber sealing gaiter surrounding the ball joint and a brake disc, and that also covers over a slot in a steering knuckle above the joint.
2. Disclosure Information
A conventional steering and suspension mechanism for a motor vehicle has a track control arm which turns a front wheel. The track control arm connects to a lower portion of a so-called knuckle which houses the wheel bearing and which also holds a disc brake. An upper portion of the knuckle has a mount for a lower end of a suspension assembly, which is connected to the track arm by a rod.
The joint between the track control arm and the knuckle is conventionally a ball joint which permits relative up and down movement of the wheel and knuckle with respect to the track arm, and which also permits the turning movement of the wheel. The ball joint conventionally has an upwardly facing socket, held at the end of the track arm, and a ball at the end of a downwardly projecting ball mounting shaft. The ball mounting shaft may be either cylindrical or frustoconical. In the latter case, the shaft will sit in a matching tapered bore in the lower portion of the knuckle, with the end of the shaft projecting through a hole and having a thread by which the ball and shaft may be tightened to the knuckle with a nut. In the former case, to which the present invention particularly relates, the knuckle has a straight bore intersected by a slot through the knuckle, and bolt is used to squeeze the knuckle slot, and hence straight bore, to fix the ball and shaft to the lower portion of the knuckle. The knuckle slot is therefore above the ball joint.
In order to keep the ball joint well lubricated, the ball joint is normally surrounded by a rubber gaiter that is packed with grease. The bottom of the gaiter is affixed to a bottom part of the end of the track control arm, and the top of the gaiter makes a sliding contact seal with an underside of the knuckle around the shaft.
In most cases, the knuckle will have affixed to it the disc of a disc brake assembly. In recent years, as cost and weight have been reduced, the spacing between the disc and the rubber gaiter has been reduced. As a result, the heat radiated by a hot disc has resulted in an increasing problem with thermal degradation over time of the rubber material of the gaiter. It is known to provide a metal heat shield between the disc and the rubber gaiter, and this shield can be affixed either to the end of the tracker arm, or to the knuckle. The present invention relates to the latter type of heat shield.
When the heat shield is mounted to the knuckle, it is necessary to align the shield with respect to the disc, because the shield cannot extend fully around the periphery of the gaiter, owing to the shape and configuration of the ball joint. The orientation of conventional heat shields is set by crimping or bending a tab of metal into a slot or against some feature of the knuckle on a face of the knuckle away from the shield and disc assembly. This process is effective at orienting the shield, but requires several process steps on a production line, namely fitting the shield between the socket and ball, turning the shield until it is oriented with the disc, and then folding or crimping the tab into place.
A problem has been noted with certain types of a ball joint and gaiter assemblies, owing to corrosion of the ball joint. Such corrosion happens when water and other contaminants enter the gaiter, and when the steering assembly is not serviced, but neglected for an extended period of time. In severe cases of corrosion, the ball can become disconnected from the socket, usually on the outer wheel during a slow speed manoeuvre at large steering angles.
The provision of a heat shield has reduced this problem by helping to preserve the gaiter. However, corrosion has still been noted as a problem, owing to water ingress into the top of the gaiter.
It is an object of the present invention to provide a protective clip that can be affixed more conveniently to a steering linkage ball joint.
It is also an object of the present invention to provide a protective clip that helps to prevent corrosion of a steering linkage ball joint.